Ibrutinib (1-[(3R)-3[4-Amino-3-(4-phenoxyphenyl)-1H-pyrazolo[3,4-d]pyrimidin-1-yl] piperidin-1-yl]prop-2-en-1one) has the following chemical structure (I):

This pharmaceutically active ingredient is known from WO 2008/039218. Ibrutinib is an inhibitor of bruton's tyrosine kinase (BTK). BTK is a key mediator of at least three critical B-cell pro-survival mechanisms occurring in parallel regulating B-cell apoptosis, cell adhesion and lymphocyte migration and homing. By inhibiting BTK ibrutinib drives B-cells into apoptosis and/or disrupts cell immigration and adherence to tumor-protective microenvironments. Ibrunitib is therefore suitable for treating chronic lymphocytic leukemia (CLL), small lymphocytic lymphoma (SLL) which are B-cell non-hodgkin lymphomas (NHL) and mantle cell lymphoma (MCL). It is marketed in the US under the name Imbruvica.
Crystalline polymorphic forms of ibrutinib are disclosed in WO 2013/184572.
Pharmaceutical formulations comprising ibrutinib are disclosed in WO 20141004707A1.
Ibrutinib has a very low solubility in water e.g. form A of ibrutinib shows according to WO 2013/184572, an observed aqueous solubility of only about 0.013 mg/ml at about pH 8. The solubility strongly depends on the pH. This results in problems in the bioavailability of the active ingredient, first because of the low solubility, and second its solubility depends on the pH value in the stomach of the patient. Particular problems arise from patients wherein the pH value is altered, e.g. due to physiological variability, diseases or premedication such as PP-inhibitors. Ibrutinib has been classified as a BCS class 2 drug and therefore, the absorption and bioavailability is primarily determined by its dissolution under physiological conditions.
WO 2013/184572, discloses further the preparation of six different crystalline forms of ibrutinib base. The existence of amorphous ibrutinib has also been mentioned but no details regarding preparation or properties are described. Three of the crystalline forms, i.e. form A, B and C are anhydrous, non-solvated forms while forms D, E and F contain either methyl isobutyl ketone, toluene or methanol, respectively.
To investigate the impact of crystalline form on physico-chemical properties, some crystalline forms of ibrutinib base, i.e. form A, form B, form C as well as amorphous ibrutinib base were prepared and characterized. Form C and amorphous ibrutinib showed substantially higher aqueous solubility compared to form A, but while stirring in suspension, a conversion into the less soluble form A was observed.
Therefore, due to the described complex polymorphism of ibrutinib base and the significant impact of solid state form on dissolution and solubility, new pharmaceutically applicable forms of ibrutinib might be useful as alternative active pharmaceutical ingredients.
Further, amorphous forms may be very difficult to purify since simple process steps like filtration or recrystallization normally do not work. Furthermore, it is very difficult to guarantee content uniformity for the active substance when processed in amorphous form into the final solid formulation. Thus amorphous forms are typically not preferred for production of tablet formulations.